Advances in software-based tools such as progressive failure analysis (PFA) tools to predict structural failure of laminated composite parts have enabled replacing expensive tests with simulations. But one of the challenges that these PFA tools have yet to overcome is that accuracy of the simulations must be demonstrated for a broad design space, test type and loading conditions. This includes correctly idealizing failure modes known to affect the failure load of a coupon during testing.
As an example, consider composites of unidirectional tape plies, a common material ply in which fibers are aligned in a single direction and imbedded in a matrix of epoxy resin. Individual plies with unique orientations are stacked together and cured to form a single laminated part. The failure load of such laminates depends not only on the response of each individual ply during loading but also interactions between them. These interactions include matrix failure modes that result from separation at the ply interfaces during loading (inter-laminar delamination), as well as fibers coming apart within a ply (intra-laminar failure).
A number of PFA tools are capable of addressing inter-laminar delamination. But there is no comparable way to deal with intra-laminar failure. It may therefore be desirable to have an apparatus and method that takes into account at least some of the issues discussed above, as well as possibly other issues.